Adherence to metformin and the onset of rheumatoid arthritis: a population-based cohort study.

Objective: The aim of this retrospective cohort study was to examine whether adherence to metformin treatment may be associated with lower onset of rheumatoid arthritis (RA).Method: Using the computerized databases of a 2.3-million state-mandated health services organization in Israel, we identified incident RA cases among a cohort of 113 749 adult patients who initiated metformin therapy between 1998 and 2014. Adherence was assessed by calculating the mean proportion of follow-up days covered (PDC) with metformin.Results: During the 18 year study period, there were 558 incident RA cases (61 per 100 000 person-years). Adherence to metformin treatment was associated with a lower risk of developing RA, with the lowest risk recorded among patients with a PDC of 40-59% [adjusted hazard ratio (HR) 0.62, 95% confidence interval (CI) 0.45-0.84] compared with non-adherent patients (PDC < 20%). A mean daily metformin dose of 2550 mg or more was also associated with a lower risk of developing RA (adjusted HR 0.62, 95% CI 0.46-0.84) compared to a daily dose of 850 mg or less. In stratified analyses by gender, the negative association between adherence and the risk of RA was limited to women alone.Conclusions: Adherence to metformin treatment is associated with a reduced risk of developing RA in women. Further studies are needed to assess the effect of metformin on RA development in other patient populations.

Decrease in 14-3-3η protein levels is correlated with improvement in disease activity in patients with rheumatoid arthritis treated with Tofacitinib.

14-3-3η protein is a proinflammatory mediator that may represent a novel diagnostic and prognostic biomarker for rheumatoid arthritis (RA). We assessed the correlation between changes in serum 14-3-3η levels and changes in clinical disease activity measures in RA patients treated with Tofacitinib (TOF). Paired serum samples from 35 patients with RA were obtained at baseline and 5 months after the initiation of treatment with TOF. The levels of 14-3-3η were measured by JOINT stat 14-3-3η ELISA test kits (Augurex Life Sciences Corp.). The cut-off was defined as 0.19 ng/ml. 14-3-3η positivity was found in 57% of the patients at baseline and in 37% of the patients after 5 months of treatment. Mean ± SD baseline 14-3-3η levels [4.92 ± 8.86 ng/ml] were significantly higher (p < 0.005) than 14-3-3η levels following treatment [1.97 ± 4.59 ng/ml]. A statistically significant improvement (p < 0.001) of CDAI, SDAI, DAS4ESR and DAS4CRP was achieved after 5 month of treatment. Decrease in 14-3-3η protein levels was highly correlated with improvement in DAS4ESR (r = 0.50, p < 0.01), DAS4CRP (r = 0.46, p < 0.01) and ESR (r = 0.36, p = 0.03) and moderately correlated with improvement in CDAI (r = 0.32, p = 0.065) and SDAI (r = 0.33, p = 0.051). The correlation between decrease in 14-3-3η levels and improvement in DAS4ESR remained significant in a partial correlation analysis controlling for ESR (r = 0.39, p = 0.02). This study demonstrates that in RA patients who were treated with TOF, decrease in 14-3-3η levels is correlated with improvement in clinical disease activity parameters. The 14-3-3η protein may serve as an objective biomarker for monitoring of TOF therapy response.

Tuftsin-phosphorylcholine (TPC) equally effective to methylprednisolone in ameliorating lupus nephritis in a mice model.

The role of helminth treatment in autoimmune diseases is growing constantly. Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease with challenging treatment options. Tuftsin-phosphorylcholine (TPC) is a novel helminth-based compound that modulates the host immune network. This study was conducted to evaluate the potential value of TPC in ameliorating lupus nephritis in a murine model and specifically to compare the efficacy of TPC to the existing first-line therapy for SLE: corticosteroids (methylprednisolone). Lupus-prone NZBxW/F1 mice were treated with TPC (5 µg/mouse), methylprednisolone (MP; 5 mg/body weight) or phosphate-buffered saline (PBS) (control) three times per week once glomerulonephritis, defined as proteinuria of grade > 100 mg/dl, was established. Levels of anti-dsDNA autoantibodies were evaluated by enzyme-linked immunosorbent assay (ELISA), splenic cytokines were measured in vitro and the kidney microscopy was analysed following staining. TPC and MP treatments improved lupus nephritis significantly and prolonged survival in NZBxW/F1 mice. TPC-treated mice showed a significantly decreased level of proteinuria (P < 0·001) and anti-dsDNA antibodies (P < 0·001) compared to PBS-treated mice. Moreover, TPC and MP inhibited the production of the proinflammatory cytokines interferon IFN-γ, interleukin IL-1ß and IL-6 (P < 0·001) and enhanced expression of the anti-inflammatory cytokine IL-10 (P < 0·001). Finally, microscopy analysis of the kidneys demonstrated that TPC-treated mice maintained normal structure equally to MP-treated mice. These data indicate that the small molecule named TPC hinders lupus development in genetically lupus-prone mice equally to methylprednisolone in most of the cases. Hence, TCP may be employed as a therapeutic potential for lupus nephritis.

Intravenous immunoglobulin: a biological corticosteroid-sparing agent in some autoimmune conditions.

Intravenous immunoglobulin (IVIg) is increasingly used for the treatment of autoimmune and systemic inflammatory diseases. This compound is effective in a wide range of clinical conditions other than primary immunodeficiency, including autoimmune diseases, inflammatory disorders, infections, organ transplantation, and possibly supportive therapy for cancer. Systemic corticosteroids remain the gold standard treatment for many autoimmune diseases, but their long-term use is associated with complications in diverse organs and systems. Osteoporosis, osteonecrosis, cardiovascular disease, infections, and cancer have been associated with this treatment. Therefore, physicians are occasionally forced to withdraw the treatment with steroids. Biological agents may represent a good alternative, but in addition to being very expensive, these agents may have serious side effects. This review aimed to cover the major advances in the use of IVIg as a steroid-sparing agent in some relevant autoimmune diseases.

Autoimmune/inflammatory syndrome induced by adjuvants (Shoenfeld's syndrome) - An update.

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) has been widely described in many studies conducted thus far. The syndrome incorporates five immune-mediated conditions, all associated with previous exposure to various agents such as vaccines, silicone implants and several others. The emergence of ASIA syndrome is associated with individual genetic predisposition, for instance those carrying HLA-DRB1*01 or HLA-DRB4 and results from exposure to external or endogenous factors triggering autoimmunity. Such factors have been demonstrated as able to induce autoimmunity in both animal models and humans via a variety of proposed mechanisms. In recent years, physicians have become more aware of the existence of ASIA syndrome and the relationship between adjuvants exposure and autoimmunity and more cases are being reported. Accordingly, we have created a registry that includes at present more than 300 ASIA syndrome cases that have been reported by different physicians worldwide, describing various autoimmune conditions induced by diverse adjuvants. In this review, we have summarized the updated literature on ASIA syndrome and the knowledge accumulated since 2013 in order to elucidate the association between the exposure to various adjuvant agents and its possible clinical manifestations. Furthermore, we especially referred to the relationship between ASIA syndrome and systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS).

Anterior ST-elevation myocardial infarction induced by rituximab infusion: A case report and review of the literature.

WHAT IS KNOWN AND OBJECTIVES: Rituximab is a chimeric monoclonal anti-CD20 antibody approved for the treatment of some lymphoid malignancies as well as for autoimmune diseases including rheumatoid arthritis (RA), idiopathic thrombocytopenic purpura (ITP) and vasculitis. Generally, rituximab is well tolerated; nevertheless, some patients develop adverse effects including infusion reactions. Albeit rare, these reactions may in some cases be life-threatening conditions. Rituximab cardiovascular side effects include more common effects such as hypertension, oedema and rare cases of arrhythmias and myocardial infarction. CASE SUMMARY: In this article, we report a case of a 58-year-old man with a history of overlap syndrome including RA and limited scleroderma who was treated with rituximab and developed a dramatic ST-elevation myocardial infarction (STEMI) during the drug administration. WHAT IS NEW AND CONCLUSION: This report underlines previous published reports emphasizing the awareness of such an association. This communication also warrants the importance of screening for ischaemic heart disease in selected cases of patients treated with rituximab.

Chilblain-like lesions (COVID-19 toes) have the same impact on family members than psoriasis systemically treated: insights from a case-control study targeting the pediatric population.

OBJECTIVE: COVID-19 toes represent the main dermatological COVID-19 cutaneous manifestation in pediatric patients. Its diagnosis exposes the whole family to social stigma and this aspect was not previously evaluated. PATIENTS AND METHODS: This was a multicenter, case-control, observational study that compared the family impact of COVID-19 toes vs. psoriasis (PsO). We enrolled 46 pediatric patients (23 with psoriasis and 23 with COVID-19 toes, age and gender matched) and their parents/caregivers that had to fill the Dermatitis Family Impact (DFI) questionnaire. RESULTS: DFI index did not differ significantly between both subgroups (p=0.48), and in psoriatic patients did not correlate with both Psoriasis Area Severity Index (PASI) (p=0.59) and itch-VAS (p=0.16). CONCLUSIONS: COVID-19 toes, a transitory dermatosis, exerted a similar impact/perturbation on family dynamics than PsO, a well-known stigmatizing, chronic inflammatory dermatosis.

Higher rates of COVID-19 but less severe infections reported for patients on Dupilumab: a Big Data analysis of the World Health Organization VigiBase.

OBJECTIVE: Dupilumab (Dupixent®) is a monoclonal antibody that inhibits IL-4 and IL-13 signaling used for the treatment of allergic diseases. Whilst biologic therapy is traditionally regarded as immunosuppressive and capable to increase the infectious risk, Dupilumab does not display these characteristics and may be even protective in certain cases. We investigated the link between Dupilumab therapy and SARS-CoV-2 infection. MATERIALS AND METHODS: We carried out a comprehensive data mining and disproportionality analysis of the WHO global pharmacovigilance database. One asymptomatic COVID-19 case, 106 cases of symptomatic COVID-19, and 2 cases of severe COVID-19 pneumonia were found. RESULTS: Dupilumab treated patients were at higher risk of COVID-19 (with an IC0.25 of 3.05), even though infections were less severe (IC0.25 of -1.71). The risk of developing COVID-19 was significant both among males and females (with an IC0.25 of 0.24 and 0.58, respectively). The risk of developing COVID-19 was significant in the age-group of 45-64 years (with an IC0.25 of 0.17). CONCLUSIONS: Dupilumab use seems to reduce COVID-19 related severity. Further studies are needed to better understand the immunological mechanisms and clinical implications of these findings. Remarkably, the heterogenous nature of the reports and the database structure did not allow to establish a cause-effect link, but only an epidemiologically decreased risk in the patients subset treated with dupilumab.

Gender differences in cardiovascular risk of patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid Arthritis (RA) is a chronic inflammatory disease, affecting women more than men, with a more aggressive course in women. DESIGN: A prospective study that recruited 58 patients (46 women aged 56 ± 12 years) with active long-standing RA disease (>12 months). Our goals were to measure their endothelial function, part of the cardiovascular risk assessment. METHODS: The Brachial Artery method measured endothelial function (the flow mediated percent change [FMD percentage] of the brachial artery diameter). A senior Rheumatologist clinically evaluated all subjects. Mann Whitney rank sum test estimated gender differences among the RA patients. RESULTS: Median FMD% change for men was -6.07%, while median FMD% change for women was 0.44% (Z = 2.38, P = 0.01). Baseline Brachial artery diameter was larger in men (Z = 2.52, P = 0.01); however, tender joints count and BMI were greater in women (Z=-2.24, P = 0.01; Z=-3.99, P = 0.001), respectively. CONCLUSIONS: Women with RA have significantly better endothelial function than men with RA. It means that even though RA is 3-fold more prevalent in women, women are more protected from atherosclerotic coronary artery disease and cardiac events.

Psoriatic and psoriatic arthritis patients with and without jet-lag: does it matter for disease severity scores? Insights and implications from a pilot, prospective study.

Background: Jet-lag may affect air-travelers crossing at least two time-zones and has several health-care implications. It occurs when the human biological rhythms are out of synch with respect to the day-night cycle at the country destination. Its effect in psoriasis is missing. We aimed to evaluate the effect of Jet-lag in psoriatic patients' management. Methods: This is a prospective observational study that enrolled psoriatic patients that underwent a flight: patients who experienced jet-lag were compared to patients who did not experience jet-lag. Before the flight, a dermatologist recorded clinical and demographical data with particular attention to Psoriasis Area Severity Index (PASI) and Disease Activity in Psoriatic Arthritis (DAPSA). Patients performed Self-Administered Psoriasis Area Severity Index (SAPASI), the Dermatology Life Quality Index (DLQI) and the pruritus Visual Analog Scale (VAS) scores. After the flight, patients completed the SAPASI, DLQI and pruritus-VAS scores. Results: The sample recruited comprised of 70 psoriatic patients aged 42.4 ± 9.7 years (median 42.5 years). Thirty (42.9%) were males, mean BMI was 25.5 ± 2.2 kg/m2. Average disease duration was 15.2 ± 7.1 years, and 20 (28.6%) subjects had developed PsA. Average hours of flight were 5.4 ± 3.5 (median 3.5 h), with 34 (48.6%) subjects reporting jet-lag. At the multivariate regression analysis, the change in the SAPASI score resulted correlated with jet-lag (regression coefficient 1.63, p = .0092), as well the change in the DLQI score (regression coefficient = 1.73, p = .0009), but no change on the pruritus VAS scale was found. Conclusions: The present study suggests that jet-lag may influence disease severity and DLQI scores, but not itch in psoriatic patients.

Inhibition of endothelial progenitor cells may explain the high cardiovascular event rate in patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) patients may suffer cardiovascular (CV) events much more than the general population, and CV disease is the leading cause of death in patients with RA. Our hypothesis was that impaired function of endothelial progenitor cells may contribute to endothelial dysfunction and the clinical CV events of patients with RA. METHODS: About 27 RA patients (9 males and 18 females) with an active disease and 13 healthy subjects who served as the control group (nine males and four females) were enrolled to this prospective study. The ability to grow in culture colony-forming units of endothelial progenitor cells (CFU-EPCs) was measured, as well as their endothelial function using high-resolution ultrasonography of the brachial artery, and levels of C reactive protein (CRP) in the serum. For statistical analysis, we used the Student's t-test. RESULTS: As a group, patients with RA were older (P < 0.0001), had severe endothelial dysfunction (P<0.0001), with impaired ability to grow CFU-EPCs (P<0.0001), and a higher inflammatory state (P = 0001). No difference was observed in BMI. All RA patients had an active disease (DAS28 3.9 ± 0.9) for 9.2 ± 6.5 years. The same differences were observed in both genders. CONCLUSIONS: Patients with RA had an impaired ability to grow EPCs and severe endothelial dysfunction. Inability to grow colonies of EPCs reflects the impaired regenerative capacity of patients with RA and may explain the endothelial dysfunction and the high CV event rate among patients with RA.

Endothelial function in rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) patients are at higher risk of accelerated atherosclerosis. AIMS: To assess endothelial dysfunction in RA to find a possible mechanistic pathway that will explain the clinical phenomenon. METHODS: A prospective study recruited 44 RA patients with an active long standing (>12 months) disease. All underwent a detailed assessment of disease activity. To estimate the endothelial function the brachial artery method was performed, measuring flow mediated diameter percent (FMD%) change. Clustering analyses (hierarchical and k-means) were performed. Patients were compared to healthy subjects. RESULTS: Forty four RA patients (54.42 ± 11.14 years, females (72.7%)) with co-morbidities (70.5%), not taking tumor necrosis factor-blockers or disease modifying anti rheumatic drugs (63.6%). Only 6 (13.6%) had a normal endothelial function. Hierarchical and k-means clustering techniques showed statistically significant differences among the three clusters concerning disease activity score-28 (DAS-28)- erythrocyte sedimentation rate (ESR) (P = 0.000), DAS-28- C-reactive protein (CRP; P = 0.001), clinical disease activity index (P = 0.002), simplified disease activity index (P = 0.001), ESR (P = 0.000), (CRP) (P = 0.003) and FMD% (P = 0.009). The group with the highest FMD% values exhibited the lowest clinical scores and laboratory parameters. Patients with the lowest FMD% values co-clustered with subjects with positive but low FMD% changes and elevated clinical and laboratory parameters. CONCLUSIONS: Our study confirmed the feasibility of exploiting endothelial function in clinical practice as an early predictor of atherosclerosis in RA patients.

The diagnostic value of 14-3-3η protein levels in patients with rheumatoid arthritis.

14-3-3η may represent a useful diagnostic biomarker for rheumatoid arthritis (RA). We assessed the prevalence and serum levels of 14-3-3η in patients with RA and in patients with other rheumatic diseases. Serum levels of 14-3-3η were measured in 96 patients with RA, in 101 patients with other rheumatic diseases, and in 66 healthy subjects. All of the sera samples were evaluated by JOINT stat 14-3-3η ELISA test kits (Augurex Life Sciences Corp.). Median (IQR) 14-3-3η levels were significantly higher in the early RA group [0.25 ng/ml (0.075-3.11)] and in patients with established RA [0.15 ng/ml (0.08-1.26)] than in healthy subjects [0 ng/ml (0-0)] and disease controls: SLE [0.01 ng/ml (0-0.055)], AS [0.05 ng/ml (0-0.255)], and PsA [0.01 ng/ml (0-0.065)]. The prevalence of 14-3-3η positivity in patients with early RA was 58%, significantly higher than that in disease controls and healthy subjects (p < 0.001). In patients with established RA, this prevalence was 43%, and it was significantly higher than that in patients with other rheumatic diseases and healthy subjects (p < 0.05), excluding the AS group (p = 0.054). In the early RA cohort, the positivity for 14-3-3η, RF, and anti-CCP was 58%, 67%, and 71%, respectively. Eighty-two percent of the patients in this cohort were positive for at least one of these biomarkers. The concentration of 14-3-3η protein may be used to distinguish between patients with early RA and patients with other rheumatic diseases.

Schizophrenia among patients with systemic lupus erythematosus: population-based cross-sectional study.

AIMS: Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease involving multiple organs, including the central nervous system. Evidence of immune dysfunction exists also in schizophrenia, a psychiatric illness involving chronic or recurrent psychosis. The aim of our study was to investigate if there is an epidemiological association between SLE and schizophrenia. METHOD: A cross-sectional study was conducted comparing patients with SLE with age and gender-matched controls regarding the proportion of patients with comorbid schizophrenia. χ 2- and t-tests were used for univariate analysis, and interaction of schizophrenia with SLE across strata of covariates was checked. A logistic regression model was used for multivariate analysis. The study was performed utilising the medical database of Clalit Health Services in Israel. RESULTS: The study included 5018 patients with SLE and 25 090 controls. SLE patients had a female predominance, and a higher proportion of smoking compared with age and sex-matched controls. In multivariate analysis, SLE was found to be independently associated with schizophrenia while controlling for age, gender, socioeconomic status (SES) and smoking (OR 1.33, p = 0.042). CONCLUSIONS: We found a positive association between SLE and schizophrenia across patients of different age, gender and SES. This association can contribute to understanding the pathophysiology of the two disorders and may also have clinical implications for earlier as well as better diagnosis and treatment.

Microprojectile bombardment-mediated transformation of Lilium longiflorum.

We have obtained transgenic lily (Lilium longiflorum) plants after microprojectile bombardment, using the Biolistics PDS 1000/He system, of morphogenic calli derived from bulblet scales, followed by bialaphos selection. Parameters which gave the highest transient uidA expression were used: a bombardment pressure of 1100 psi, a target distance of 6 cm and a 48-h preculture on medium with 3% sucrose. A total of 1800 morphogenic calli were co-bombarded with plasmids containing either the uidA reporter or PAT selectable marker genes. After bombardment, the calli were exposed to 2 mg/l bialaphos. Only 72 of the shoot-forming calli (4%) survived. The 72 shoot clusters produced 342 shoots on elongation medium containing 0.5 mg/l bialaphos. Only 55 plantlets survived subsequent exposure to 2.0 mg/l bialaphos. PCR analysis indicated that 19 of these plantlets contained the PAT transgene. Southern analysis of 3 of the plants indicated that all contained the PAT gene.

Improvement of Aconitum napellus micropropagation by liquid culture on floating membrane rafts.

An efficient method was developed using floating membrane rafts (Liferaft(™)) for the micropropagation of Aconitum napellus (Ranunculaceae), a cut flower crop with a low natural propagation rate. This was achieved by introducing shoot tips into culture on Murashige and Skoog's (1962) solid medium, or liquid medium-supported rafts, supplemented by different levels of benzyl adenine (BA). Optimum shoot proliferation on solid medium required 4mg/l BA, whereas for expiants supported on rafts optimal proliferation was achieved at 0.25mg/l BA. Maximum shoot proliferation was found using the floating rafts (propagation ratio of 4.2 per month), 45% higher than the maximum value on solid medium. A similar value could be obtained on solid medium after a period of 2 months. The optimal response to BA was similar for fresh weight gain and shoot length. Growth in a shallow layer of liquid in shake flasks gives a similar shoot multiplication rate to that on floating rafts; however, submerged leaves brown and die.

Comparison between a Stable NaCl-Selected Nicotiana Cell Line and the Wild Type : K, Na, and Proline Pools as a Function of Salinity.

An NaCl-resistant line has been developed from suspension-cultured tobacco cells (Nicotiana tabacum/gossii) by stepwise increases in the NaCl concentration in the medium. Resistance showed stability through at least 24 generations in the absence of added NaCl.Above an external NaCl concentration of 35 millimolar, proline concentration in the selected cells rose steeply with external NaCl, particularly so above 100 millimolar NaCl. Proline accumulation in the wild type was far slighter. Selected cells which had been grown for 24 generations in the absence of added NaCl accumulated proline strongly on re-exposure to NaCl medium, indicating stability of this character. Proline accumulation was fully reversible with a half-time of about 6 hours. When selected cells were transferred sequentially to lower and lower NaCl concentrations, their proline content fell to the level corresponding to the new NaCl concentration. The NaCl-selected cells responded to water stress (i.e. added mannitol) by accumulating markedly more proline than did the wild type.The addition of Ca(2+) to the growing and rinsing media minimized Na(+) and K(+) binding in the Donnan free space of cell walls and thus allowed assessment of intracellular Na(+) and K(+). In both cell types, internal Na(+) content rose steadily as a function of external NaCl concentration. In the course of 7 days in NaCl media, the wild type cells lost a considerable part of their K(+) content, the extent of the loss increasing with rise in external NaCl concentration. The selected cells, by contrast, lost no K(+) at external NaCl concentrations below 50 millimolar external NaCl, and at higher concentrations lost less than the wild type.

Enhanced Net K Uptake Capacity of NaCl-Adapted Cells.

Maintenance of intracellular K(+) concentrations that are not growth-limiting, in an environment of high Na(+), is characteristic of NaCl-adapted cells of the glycophyte, tobacco (Nicotiana tabacum/gossii). These cells exhibited a substantially greater uptake of (86)Rb(+) (i.e. an indicator of K(+)) relative to unadapted cells. Potassium uptake into NaCl-adapted cells was 1.5-fold greater than unadapted cells at 0 NaCl and 3.5-fold greater when cells were exposed to 160 millimolar NaCl. The difference in net K(+) uptake between unadapted and NaCl-adapted cells was due primarily to higher rates of entry rather than to reduced K(+) leakage. Presumably, enhanced K(+) uptake into adapted cells is a result of electrophoretic flux, and a component of uptake may be linked to vanadate-sensitive H(+) extrusion.

Proton Fluxes as a Response to External Salinity in Wild Type and NaCl-Adapted Nicotiana Cell Lines.

Addition of 100 millimolar KCl, NaCl, or Na(2)SO(4) strongly promoted acidification of the medium by cells of Nicotiana tabacum/gossii in suspension culture. Acidification was greater in the case of NaCl-adapted than in that of wild type cells, and strikingly so in KCl medium when fusicoccin (FC) was present. Back-titration indicated that net proton secretion in KCl medium was increased 4-fold by FC treatment in the case of adapted cells; but was not even doubled in wild type cells. Membrane potential was higher in NaCl-adapted cells. FC treatment hyperpolarized wild, but not NaCl-adapted cells, suggesting a higher degree of coupling between H(+) efflux and K(+) influx in adapted cells; FC enhanced net K(+) uptake in adapted but not in wild cells. Acidification by cells suspended in 10 millimolar KCl was highly sensitive to vanadate, but that after addition of 100 millimolar KCl or NaCl was much less sensitive. Addition of 100 millimolar NaCl to wild type cells already provided with 10 millimolar KCl briefly accelerated, then slowed down the rate of acidification. If the addition was made after acidification had already ceased, alkalization was observed, particularly in the presence of FC. The results are consistent with the operation of a Na(+)-H(+) antiporter.